万以下的自动返回,我添加了 万/百万/千万/亿 的单位,可以根据自己的需求进行单位修改,
参考来源

+(NSString *)getDealNumwithstring:(NSString *)string{
    NSDecimalNumber *numberA = [NSDecimalNumber decimalNumberWithString:string];
    NSDecimalNumber *numberB ;
    NSString *unitStr;
    if (string.length > 3 && string.length <7 ) {
        numberB =  [NSDecimalNumber decimalNumberWithString:@"10000"];
        unitStr = @"万";
    }else if (string.length ==7){
        numberB =  [NSDecimalNumber decimalNumberWithString:@"1000000"];
        unitStr = @"百万";
    }else if(string.length ==8){
        numberB =  [NSDecimalNumber decimalNumberWithString:@"10000000"];
        unitStr = @"千万";
    }
    else if (string.length > 8){
        numberB =  [NSDecimalNumber decimalNumberWithString:@"100000000"];
        unitStr = @"亿";
    }else{
        return string;
    }
    //NSDecimalNumberBehaviors对象的创建  参数 1.RoundingMode 一个取舍枚举值 2.scale 处理范围 3.raiseOnExactness  精确出现异常是否抛出原因 4.raiseOnOverflow  上溢出是否抛出原因  4.raiseOnUnderflow  下溢出是否抛出原因  5.raiseOnDivideByZero  除以0是否抛出原因。
    NSDecimalNumberHandler *roundingBehavior = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundDown scale:1 raiseOnExactness:NO raiseOnOverflow:NO raiseOnUnderflow:NO raiseOnDivideByZero:NO];
    
    /// 这里不仅包含Multiply还有加 减 乘。
    NSDecimalNumber *numResult = [numberA decimalNumberByDividingBy:numberB withBehavior:roundingBehavior];
    NSString *strResult = [NSString stringWithFormat:@"%@%@",[numResult stringValue],unitStr];
    return strResult;
}